Hormones and Stress: what the experts say

The Big Picture

Across these conversations, stress hormones come out as neither good nor bad in themselves. What matters is how long they stay raised. Andrew Huberman describes cortisol and epinephrine as hormones of energy [1], and his overarching message is that stress is not good or bad in itself: well-timed cortisol and brief, deliberate spikes of adrenaline can raise energy, strengthen immunity and help cement memory, while chronic stress flips hormonal feedback loops, drives comfort eating, grays hair and weakens immunity [2]. On The Mel Robbins Podcast, Swart makes the same split from the other side. Cortisol, the stress hormone, isn't all bad: it helps us wake up and dodge a speeding car, and then it should drop back to normal [3]. The trouble she describes is that modern life's flood of information and psychological threats keeps cortisol near the top of its range all the time [3].

The biology behind this is laid out by Huberman. Cortisol is a steroid hormone made from cholesterol, like estrogen and testosterone, and it competes with them for that raw material, so when you are stressed, more cholesterol is diverted toward cortisol [1]. The release chain starts in the brain with corticotropin-releasing hormone (CRH), which tells the pituitary to release ACTH, which in turn tells the adrenal glands above the kidneys to release cortisol [1]. Duncan French, the guest on Huberman Lab, adds that the body runs one response for many triggers: holding your hand near a flame, jumping in an ice bath, facing a lion or doing a hard workout all set off the same adrenaline cascade [4].

Where the Experts Agree

Short stress is useful. Huberman presents brief daytime stress as support for learning and neuroplasticity, and short-term adrenaline as a boost to immune defense [1]. Swart says cortisol helps us wake up and react to danger [3]. Summing up his conversation with French, Huberman says discomfort is beneficial, as long as the stress doesn't go on too long [4].
Long stress does damage. Huberman lists a runaway feedback loop, comfort-food cravings and gray hair among the harms of chronic stress [1], along with weaker immunity [2]. Swart describes cortisol as a corrosive agent flowing through brain and body that erodes immunity, from colds that linger for weeks all the way to heart attacks and cancers [3].
Immunity moves in both directions. A brief adrenaline spike is described as strengthening immune defense [1][2], while chronically high cortisol is described as wearing it down [2][3].
The body does not sort stressors by type. French says cold, heat, threat and hard training trigger the same cascade: "Your body does not know the difference" [4]. Huberman groups cold, cyclic breathing and high-intensity exercise together as deliberate stressors [1].

Where They Differ

The speakers largely agree; the differences are in emphasis and in what they warn about.

Huberman's emphasis is on using the hormones as tools: time the cortisol peak with morning sunlight, then use cold, breathing or exercise to energize yourself and strengthen immunity [2]. Swart's emphasis is on the cost of cortisol that never comes down. She says receptors in the brain read constant high levels as an imminent threat to survival, and because we're wired "in such a cave person way", the brain assumes the threat is starvation and stores extra fat in the abdomen [3]. In her words, "it's not just causing fat, it's specifically causing belly fat", and diet and exercise may not shift it while cortisol stays high [3]. She also describes the brain going into a low power mode, with blood supply pulled from higher functions like creative thinking, solving complex problems, overriding biases and regulating emotions [3].

Cold exposure is where the trade-off is sharpest. Huberman lists cold among the deliberate stressors that build energy and resilience [1]. French accepts cold as a mental stressor to practice managing, but separates that from using it as a physiological recovery tool [4]. For recovery, he says cold clamps down the whole vascular system, the evidence on what it does to muscle is still unsettled, and there are now robust data that cold can reduce strength, power and muscle growth by dampening mTOR and other growth signaling [4].

Huberman also puts a limit on his own tools. If you feel exhausted and burned out, he says those same tools push you deeper into chronic stress, and you may need a warm bath instead of an ice bath, better sleep and possibly ashwagandha [2]. French adds a different limit: repeated exposure to the same challenge produces less stress response over time, so the stress must evolve [4].

Practical Takeaways

Time your daily cortisol peak with morning sunlight; Huberman gives specific durations by cloud cover [1][2].
Use brief, deliberate stressors such as cold, cyclic breathing or high-intensity exercise to raise energy, and keep them brief [1][2].
Place an adrenaline spike right after learning to help cement the memory, as Huberman suggests [2].
Practice keeping the mind calm while the body is activated, which Huberman says gives you real control over your energy, health and performance [2].
Be clear about why you use cold: as a mental stressor to practice managing, or as a recovery tool, where French says it can reduce strength, power and muscle growth [4].
If you are exhausted and burned out, skip the ice bath; Huberman points to a warm bath, better sleep and possibly ashwagandha instead [2].
Watch for the signs of chronic cortisol that Swart names: a tighter belt with no other change in shape, and colds that linger for weeks [3].
Treat ashwagandha and apigenin as optional support, behind sleep, light and stress-regulation practices [2].